though its unfair that frostwyrm is in the gladiator series, frostwyrm should be a lich king drop, theres like 40 raiders and the chanse of all getting one is VEEEERY low and frostwyrm kinda is arthas' dragon

It's 25 raiders, and it doesn't depend on your luck. Protodrakes from Naxx and Ulduar required doing some achievements tied to the bosses, and everyone who completed them received the mount. IC probably won't be different.

it dies, gets resurrected, rode on without breaks until you come to kill its only friend in undeath (and probably life), then pry it away from its rightful owner, and then sit on it with your big tauren butt.

it dies, gets resurrected, rode on without breaks until you come to kill its only friend in undeath (and probably life), then pry it away from its rightful owner, and then sit on it with your big tauren butt.